package io.renren.wechat.common.aes;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Random;

/**
 * 提供接收和推送给企业微信消息的加解密接口(UTF8编码的字符串).
 * <ol>
 * 	<li>第三方回复加密消息给企业微信</li>
 * 	<li>第三方收到企业微信发送的消息，验证消息的安全性，并对消息进行解密。</li>
 * </ol>
 * 说明：异常java.security.InvalidKeyException:illegal Key Size的解决方案
 * <ol>
 * 	<li>在官方网站下载JCE无限制权限策略文件（JDK7的下载地址：
 *      http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html</li>
 * 	<li>下载后解压，可以看到local_policy.jar和US_export_policy.jar以及readme.txt</li>
 * 	<li>如果安装了JRE，将两个jar文件放到%JRE_HOME%\lib\security目录下覆盖原来的文件</li>
 * 	<li>如果安装了JDK，将两个jar文件放到%JDK_HOME%\jre\lib\security目录下覆盖原来文件</li>
 * </ol>
 */

public class WXBizCorpCrypt {
    private static final Logger LOGGER = LoggerFactory.getLogger(WXBizCorpCrypt.class);
    private static final Charset CHARSET = StandardCharsets.UTF_8;
    private final Base64 base64 = new Base64();
    private final byte[] aesKey;
    private final String token;
    private final String receiveid;

    /**
     * 构造函数
     *
     * @param token          企业微信后台，开发者设置的token
     * @param encodingAesKey 企业微信后台，开发者设置的EncodingAESKey
     * @param corpId,     不同场景含义不同，详见文档
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public WXBizCorpCrypt(String token, String encodingAesKey, String corpId) throws AesException {
        if (encodingAesKey.length() != 43) {
            throw new AesException(AesException.IllegalAesKey);
        }

        this.token = token;
        this.receiveid = corpId;
        aesKey = Base64.decodeBase64(encodingAesKey + "=");
    }

    // 生成4个字节的网络字节序
    byte[] getNetworkBytesOrder(int sourceNumber) {
        byte[] orderBytes = new byte[4];
        orderBytes[3] = (byte) (sourceNumber & 0xFF);
        orderBytes[2] = (byte) (sourceNumber >> 8 & 0xFF);
        orderBytes[1] = (byte) (sourceNumber >> 16 & 0xFF);
        orderBytes[0] = (byte) (sourceNumber >> 24 & 0xFF);
        return orderBytes;
    }

    // 还原4个字节的网络字节序
    int recoverNetworkBytesOrder(byte[] orderBytes) {
        int sourceNumber = 0;
        for (int i = 0; i < 4; i++) {
            sourceNumber <<= 8;
            sourceNumber |= orderBytes[i] & 0xff;
        }
        return sourceNumber;
    }

    // 随机生成16位字符串
    String getRandomStr() {
        String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 16; i++) {
            int number = random.nextInt(base.length());
            sb.append(base.charAt(number));
        }
        return sb.toString();
    }

    /**
     * 对明文进行加密.
     *
     * @param text 需要加密的明文
     * @return 加密后base64编码的字符串
     * @throws AesException aes加密失败
     */
    String encrypt(String randomStr, String text) throws AesException {
        ByteGroup byteCollector = new ByteGroup();
        byte[] randomStrBytes = randomStr.getBytes(CHARSET);
        byte[] textBytes = text.getBytes(CHARSET);
        byte[] networkBytesOrder = getNetworkBytesOrder(textBytes.length);
        byte[] receiveidBytes = receiveid.getBytes(CHARSET);

        // randomStr + networkBytesOrder + text + receiveid
        byteCollector.addBytes(randomStrBytes);
        byteCollector.addBytes(networkBytesOrder);
        byteCollector.addBytes(textBytes);
        byteCollector.addBytes(receiveidBytes);

        // ... + pad: 使用自定义的填充方式对明文进行补位填充
        byte[] padBytes = PKCS7Encoder.encode(byteCollector.size());
        byteCollector.addBytes(padBytes);

        // 获得最终的字节流, 未加密
        byte[] unencrypted = byteCollector.toBytes();

        try {
            // 设置加密模式为AES的CBC模式
            Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
            SecretKeySpec keySpec = new SecretKeySpec(aesKey, "AES");
            IvParameterSpec iv = new IvParameterSpec(aesKey, 0, 16);
            cipher.init(Cipher.ENCRYPT_MODE, keySpec, iv);

            // 加密
            byte[] encrypted = cipher.doFinal(unencrypted);

            // 使用BASE64对加密后的字符串进行编码

            return base64.encodeToString(encrypted);
        } catch (Exception e) {
            e.printStackTrace();
            throw new AesException(AesException.EncryptAESError);
        }
    }

    /**
     * 对密文进行解密.
     *
     * @param text 需要解密的密文
     * @return 解密得到的明文
     * @throws AesException aes解密失败
     */
    String decrypt(String text) throws AesException {
        byte[] original;
        try {
            // 设置解密模式为AES的CBC模式
            Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
            SecretKeySpec key_spec = new SecretKeySpec(aesKey, "AES");
            IvParameterSpec iv = new IvParameterSpec(Arrays.copyOfRange(aesKey, 0, 16));
            cipher.init(Cipher.DECRYPT_MODE, key_spec, iv);

            // 使用BASE64对密文进行解码
            byte[] encrypted = Base64.decodeBase64(text);

            // 解密
            original = cipher.doFinal(encrypted);
        } catch (Exception e) {
            e.printStackTrace();
            throw new AesException(AesException.DecryptAESError);
        }

        String xmlContent, from_receiveid;
        try {
            // 去除补位字符
            byte[] bytes = PKCS7Encoder.decode(original);

            // 分离16位随机字符串,网络字节序和receiveid
            byte[] networkOrder = Arrays.copyOfRange(bytes, 16, 20);

            int xmlLength = recoverNetworkBytesOrder(networkOrder);

            xmlContent = new String(Arrays.copyOfRange(bytes, 20, 20 + xmlLength), CHARSET);
            from_receiveid = new String(Arrays.copyOfRange(bytes, 20 + xmlLength, bytes.length),
                    CHARSET);
        } catch (Exception e) {
            e.printStackTrace();
            throw new AesException(AesException.IllegalBuffer);
        }

        // receiveid不相同的情况
        if (!from_receiveid.equals(receiveid)) {
            throw new AesException(AesException.ValidateCorpidError);
        }
        return xmlContent;

    }

    /**
     * 将企业微信回复用户的消息加密打包.
     * <ol>
     * 	<li>对要发送的消息进行AES-CBC加密</li>
     * 	<li>生成安全签名</li>
     * 	<li>将消息密文和安全签名打包成xml格式</li>
     * </ol>
     *
     * @param replyMsg  企业微信待回复用户的消息，xml格式的字符串
     * @param timeStamp 时间戳，可以自己生成，也可以用URL参数的timestamp
     * @param nonce     随机串，可以自己生成，也可以用URL参数的nonce
     * @return 加密后的可以直接回复用户的密文，包括msg_signature, timestamp, nonce, encrypt的xml格式的字符串
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public String EncryptMsg(String replyMsg, String timeStamp, String nonce) throws AesException {
        // 加密
        String encrypt = encrypt(getRandomStr(), replyMsg);

        // 生成安全签名
        if (StringUtils.isBlank(timeStamp)) {
            timeStamp = Long.toString(System.currentTimeMillis());
        }

        String signature = SHA1.getSHA1(token, timeStamp, nonce, encrypt);

        // System.out.println("发送给平台的签名是: " + signature[1].toString());
        // 生成发送的xml
        return XMLParse.generate(encrypt, signature, timeStamp, nonce);
    }

    /**
     * 检验消息的真实性，并且获取解密后的明文.
     * <ol>
     * 	<li>利用收到的密文生成安全签名，进行签名验证</li>
     * 	<li>若验证通过，则提取xml中的加密消息</li>
     * 	<li>对消息进行解密</li>
     * </ol>
     *
     * @param msgSignature 签名串，对应URL参数的msg_signature
     * @param timeStamp    时间戳，对应URL参数的timestamp
     * @param nonce        随机串，对应URL参数的nonce
     * @param postData     密文，对应POST请求的数据
     * @return 解密后的原文
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public String DecryptMsg(String msgSignature, String timeStamp, String nonce, String postData)
            throws AesException {

        // 密钥，公众账号的app secret
        // 提取密文
        Object[] encrypt = XMLParse.extract(postData);

        // 验证安全签名
        String signature = SHA1.getSHA1(token, timeStamp, nonce, encrypt[1].toString());

        /*
         和URL中的签名比较是否相等
         System.out.println("第三方收到URL中的签名：" + msg_sign);
         System.out.println("第三方校验签名：" + signature);
        */
        if (!signature.equals(msgSignature)) {
            throw new AesException(AesException.ValidateSignatureError);
        }

        // 解密
        return decrypt(encrypt[1].toString());
    }

    /**
     * 验证URL
     *
     * @param msgSignature 签名串，对应URL参数的msg_signature
     * @param timeStamp    时间戳，对应URL参数的timestamp
     * @param nonce        随机串，对应URL参数的nonce
     * @param echoStr      随机串，对应URL参数的echoStr
     * @return 解密之后的echoStr
     * @throws AesException 执行失败，请查看该异常的错误码和具体的错误信息
     */
    public String VerifyURL(String msgSignature, String timeStamp, String nonce, String echoStr)
            throws AesException {
        LOGGER.debug("using token={}, msgSignature={}, timeStamp={}, nonce={}, echoStr={}", token, msgSignature, timeStamp, nonce, echoStr);

        String signature = SHA1.getSHA1(token, timeStamp, nonce, echoStr);

        LOGGER.debug("calc signature: {}", signature);

        if (!signature.equals(msgSignature)) {
            throw new AesException(AesException.ValidateSignatureError);
        }

        return decrypt(echoStr);
    }

    // msgSignature=[d258f67d67e4dd3b9e1d40670c40478969405857], timestamp=[1637121570], nonce=[1637175680],
    // echostr=[YlZ+NY7DnjXaH3eFFZETfxQUcANjVZO+DfwDYN2J6k9M5tH47F8O6R5g4sVQFb0F96Ttt3AvSIyGlHqp47yO4w==]
    public static void main(String[] args) throws Exception {
        String corpId = "ww4f8a11931c91b281";
        String suiteId = "wwa11becac8855d919";
        String corpToken = "OSR9w6EpFF8B3InvQtVP5hjtN2Cw";
        final String corpEncodingAesKey = "VRWzJwMV8K1Ag70OTavWMcUkTGABFnvVpARBkXdBHgv";

        String suiteToken = "0GjzZvAeHjm12Dv3a4KhR3h";
        final String suiteEncodingAesKey = "YYgVbAOKdPM8UTfM8C7dk7X2vZvEQzazZhRd1KC1s5K";

        String msgSignature = "51394dac2ccd89317d55135bce73c8c56d9be577";
        String timeStamp = "1637494602";
        String nonce = "1637585205";
        String postData = "<xml><ToUserName><![CDATA[ww1c8d2ae2652278df]]></ToUserName><Encrypt><![CDATA[EsTCbh0SMQZknL+J0mwd2By9to6XW9Ug5+nSNBBGz8jv6pvjwK/zFDTDvkOBFwp8AN21pZODPGBKq8Y7VSntz0qudWZZ48up1djrSASpQds9C7QVhO3MAu4DFJaJIQ+W4b+ppogO7Z474xP85wFbdT9koEHrs6sonGL3SxpOSSmM/x50LGsjpGe5MNgm2AVOJs9fRCLPt9M6lf65aJjjhwUx0QjMYUL5p97yao3nMkP6CS0eheVWS1HvBf3XlAi6TIB7YFk8zuH3aukfDOBWyKS6h3q0VpvdER5JCXwrHuDtDnZnjD4DYUgIyJijwMOqKpN0lzERjskeaGdkahOzY9dKct2l7TBb36Rc0pGsXgtlfTG9tPQV1h5yS24Fa483jfzHg0BVKxRcXB4hMfsoa23l59YvJFwj7Biw3xvY3xg=]]></Encrypt><AgentID><![CDATA[1000003]]></AgentID></xml>";

        String echoStr = "YlZ+NY7DnjXaH3eFFZETfxQUcANjVZO+DfwDYN2J6k9M5tH47F8O6R5g4sVQFb0F96Ttt3AvSIyGlHqp47yO4w==";

        //WXBizCorpCrypt wxBizMsgCrypt = new WXBizCorpCrypt(suiteToken, suiteEncodingAesKey, suiteId);
        WXBizCorpCrypt wxBizMsgCrypt = new WXBizCorpCrypt(corpToken, corpEncodingAesKey, corpId);

        //String signature = SHA1.getSHA1(corpToken, timeStamp, nonce, echoStr);
        //System.out.println(msgSignature.equals(signature));

        final String decrypt = wxBizMsgCrypt.DecryptMsg(msgSignature, timeStamp, nonce, postData);
        System.out.println(decrypt);
    }

}